Full list of all 23 Sonic The Hedgehog achievements worth 1,000 gamerscore. It takes around 60-80 hours to unlock all of the achievements on Xbox 360.
You have Cleared Sonic Episode.
You have Cleared Silver Episode.
You have Cleared all Sonic ACT Missions.
You have Achieved S Rank on all Sonic ACT Missions.
You have Learned all Silver actions.
You have Received all Gold Medals of Soleanna.
You have Achieved S Rank on all ACT Missions.
You have Achieved S Rank on all Last Episode.
You have Cleared Last Episode.
You have Received all Silver Medals of Soleanna.
You have Achieved S Rank on all Shadow ACT Missions.
You have Cleared all Shadow ACT Missions.
You have Achieved Rank S on all Shadow TOWN Missions.
You have Cleared all Shadow TOWN Missions.
You have Cleared Shadow Episode.
You have Learned all Shadow actions.
You have Achieved S Rank on all Silver ACT Missions.
You have Cleared all Silver ACT Missions.
You have Achieved Rank S on all Silver TOWN Missions.
You have Cleared all Silver TOWN Missions.
You have Learned all Sonic actions.
You have Achieved Rank S on all Sonic TOWN Missions.
You have Cleared all Sonic TOWN Missions.